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TVEM SAS Macro for Estimating a Time-Varying Effect Model

This program is free software; you can redistribute it and/or modify it under the terms described below.

WARRANTY

This software is provided "as is," and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose, are expressly disclaimed. In no event shall Penn State University or its employees be liable for any direct, indirect, incidental, special, exemplary, or consequential damages (including, but not limited, the costs of procurement of substitute goods or services; loss of use, data or profits; or business interruption) however caused and on any theory of liability, whether in contract, strict liability, or tort (including negligence or otherwise) arising in any way out of the use of this software, even if advised in advance of the possibility of such damage.

PUBLICATIONS

Any peer-reviewed publication in which this software is used will include a citation of the software in the reference section. Sample citations in APA format will be available on The Methodology Center website for as long as the software is supported by the center.

REDISTRIBUTION

Redistribution and use of this software, with or without modification, are permitted, provided that the following conditions are met:

1. Any redistribution must include the above copyright notice and disclaimer and this list of conditions in any related documentation and, if feasible, in the redistributed software.

2. Any redistribution must include the acknowledgment, "This product includes software developed by Methodology Center, The Pennsylvania State University," in any related documentation and, if feasible, in the redistributed software.

3. The names "Penn State" and "Penn State University", and “The Pennsylvania State University” are trademarks of The Pennsylvania State University and may not be used in association with any goods or services, including products derived from these materials, without the prior express written agreement of The Pennsylvania State University.

OTHER TERMS

By downloading this software, you are agreeing to abide by the terms and conditions contained herein. By downloading, you are obtaining a non-exclusive license to use these materials in accordance with these terms. Nothing contained herein shall be deemed a waiver of any rights by The Pennsylvania State University in these materials.

This program is free software; you can redistribute it and/or modify it under the terms described below.

WARRANTY

This software is provided "as is," and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose, are expressly disclaimed. In no event shall Penn State University or its employees be liable for any direct, indirect, incidental, special, exemplary, or consequential damages (including, but not limited, the costs of procurement of substitute goods or services; loss of use, data or profits; or business interruption) however caused and on any theory of liability, whether in contract, strict liability, or tort (including negligence or otherwise) arising in any way out of the use of this software, even if advised in advance of the possibility of such damage.

PUBLICATIONS

Any peer-reviewed publication in which this software is used will include a citation of the software in the reference section. Sample citations in APA format will be available on The Methodology Center website for as long as the software is supported by the center.

REDISTRIBUTION

Redistribution and use of this software, with or without modification, are permitted, provided that the following conditions are met:

1. Any redistribution must include the above copyright notice and disclaimer and this list of conditions in any related documentation and, if feasible, in the redistributed software.

2. Any redistribution must include the acknowledgment, "This product includes software developed by Methodology Center, The Pennsylvania State University," in any related documentation and, if feasible, in the redistributed software.

3. The names "Penn State" and "Penn State University", and “The Pennsylvania State University” are trademarks of The Pennsylvania State University and may not be used in association with any goods or services, including products derived from these materials, without the prior express written agreement of The Pennsylvania State University.

OTHER TERMS

By downloading this software, you are agreeing to abide by the terms and conditions contained herein. By downloading, you are obtaining a non-exclusive license to use these materials in accordance with these terms. Nothing contained herein shall be deemed a waiver of any rights by The Pennsylvania State University in these materials.

Overview

For use with SAS Version 9.2 or higher for Windows.

The TVEM SAS macro estimates coefficients in a time-varying effect model. Traditional analytic methods assume that covariates have constant (i.e., time-invariant) effects on a time-varying outcome. The %TVEM macros are able to estimate the time-varying effects of covariates. TVEM is a convenient tool for several types of data.

Features of the TVEM SAS macro

Option to include multiple non-time-varying covariates

Option to include multiple time-varying covariates

Ability to accommodate of different distributions (normal, logistic, or Poisson) measured over time

Option to employ a penalized truncated power spline basis instead of a B-spline basis function

Ability to model within-subject correlation using random effects or a robust sandwich variance estimator New in version 3.1.0

Enhanced screen output for improved interpretability New in version 3.1.0

Multiple optional output datasets New in version 3.1.0

The %TVEM_zip for outcomes (v 2.1.1) is available separately to fit zero-inflated Poisson models.